Where have Spring and Fall Gone? Changes in Temperate Transition Season Days

Keywords: apparent temperature, thermohygrometric index
Abstract Type: Poster Abstract

Abstract

Anecdotal evidence suggests that temperate transition season days are less numerous in recent years, with abrupt shifts directly from winter to summer or summer to winter becoming more common. In this work we examine this phenomenon for St. Louis, MO using two measures of human thermal comfort: apparent temperature (AT) and thermohygrometric index (THI). Several thresholds for AT and THI are used to examine the occurrence of “comfortable” hours that would be expected during the transition seasons. Results indicate there are recurring themes in which months are experiencing the greatest changes, regardless of metric or time of day. Depending on the measure, there is evidence that the number of “comfortable” hours are decreasing on an annual basis. In addition, the seasonality and diurnal patterns of these “comfortable” hours are changing which may further the perception of fewer “comfortable” days. Future work will expand this work to additional locations and using other thermal comfort indices.